1. Field of the Invention
The invention relates to a feed unit for a fuel tank, in particular for a motor vehicle, the feed unit including a baffle, with a fuel pump and with a filter preceding the fuel pump.
2. Description of the Prior Art
Feed units which are to be used in fuel tanks and by means of which fuel is fed from the tank to the internal combustion engine of the motor vehicle are generally known and are therefore state of the art. The fuel pump arranged in the baffle sucks in the fuel from the baffle via the filter. Impurities in the fuel are to be prevented by means of the filter from passing into the fuel pump and from there to the internal combustion engine.
DE 36 09 906 A1 discloses a filter of this type. It consists of a tubular filter fabric which is connected to a connection piece and via which the filter is fastened to the inlet port of the fuel pump. The filter is led as far as the bottom of the tank, so that, even when the liquid level is low, fuel can be sucked in by the fuel pump over part of the filter fabric. In order to avoid the filter being contracted as a result of the suction effect of the fuel pump, thereby impairing the filter action, a supporting body is inserted into the filter fabric and prevents the filter from being contracted.
The complicated manufacture of the filter is a particular disadvantage. Thus, the insertion of the supporting body, the shaping of the filter fabric into its final shape and the welding of the edges of the filter fabric necessitate a multiplicity of work steps. In addition, there is the orientation of the filter during the mounting of the latter in the tank.
The object of the present invention is to provide a filter for a fuel pump of the type initially mentioned which has a better filter capacity, is simple to produce and can be mounted easily.
This object is met according to the invention, in that the filter is integrated into the baffle of the feed unit. Part of the baffle is in this case an integral part of the filter in that it is covered by the filter fabric. This part of the baffle thus forms the filter housing. The decisive advantage is that the useful filter surface is enlarged, thus entailing an improved filter capacity. In addition, in this case, the fuel also passes into the filter as a result of gravity, no longer solely due to the suction capacity of the fuel pump. A tubular closed configuration of the filter fabric being avoided, the production of the filter fabric is appreciably simpler and therefore, cost-effective.
In an embodiment of the present invention, the filter fabric covers a part region of the bottom of the baffle. A particularly reliable fuel supply is ensured when this part region is the lowest region of the baffle. The part region may at the same time have a step-shaped or outwardly curved design. In the case of a baffle without an orifice in the bottom, the entire bottom is advantageously covered by the filter fabric. A particularly large filter surface is thereby obtained.
In order to prevent the filter from being contracted, it is advantageous to arrange supporting elements between the baffle and the filter fabric. A favorable configuration is obtained when these supporting elements, ribs, are connected to the baffle. The supporting elements may both be snapped in and be integrally molded. In another configuration, the supporting elements are arranged on the filter fabric and support the latter against the baffle.
The fastening of the filter fabric in the baffle becomes particularly simple when the filter fabric is surrounded by a frame. Latching elements arranged on the frame make particularly simple mounting possible when they are snapped together with latching points in the baffle. An even simpler refinement, with the filter fabric being sealed off effectively relative to the baffle, is obtained when the frame is snapped into a peripheral groove arranged in the baffle.
In another refinement, the frame is made of plastic and is inserted in a receptacle of the baffle. As a result of the swelling of the plastic, the frame is pressed together with the receptacle, so that the sealing effect occurs.
It is also advantageous to insert the filter fabric into the baffle and fasten it to the baffle by means of a holding ring. In a further refinement, the filter fabric is welded to the baffle. Support, at the same time with the filter fabric being fixed, is achieved in that the supporting elements have latching points, into which latching elements arranged on the filter fabric engage.